M4.5 Earthquake 158 km S of False Pass, Alaska — October 21, 2026
2026-10-21 12:03:56 UTC (2 hours ago) · approx. 1:03 AM UTC-11 local
On October 21, 2026 at 12:03 UTC, a magnitude 4.5 shallow crustal earthquake struck 158 km S of False Pass, Alaska, at a depth of 20.5 km and coordinates 53.4261°, -163.4612°. This earthquake was detected by 94 seismic stations with good location accuracy and was assigned a USGS significance rating of 312, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 4.5 releases seismic energy equivalent to roughly 85 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 767 m — a useful intuition for the size of the slip patch on the fault.
The epicenter is located in Alaska, a region characterized by Pacific Plate subduction beneath the North American Plate, producing frequent megathrust and crustal earthquakes along the Aleutian arc. The nearest mapped fault system is the Aleutian megathrust. View all earthquakes in Alaska.
Learn more: Magnitude scale · Aftershock sequences
Earthquake Details
-163.4612°E
Technical Information
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Common Questions
How strong was the magnitude 4.5 earthquake near False Pass, Alaska?
The magnitude 4.5 earthquake that struck 158 km S of False Pass, Alaska on October 21, 2026 at 12:03 UTC had a depth of 20.5 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 53.4261°, -163.4612°, which is 158 km S of False Pass, Alaska. View all earthquakes in Alaska.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.5 earthquakes can continue for several days and gradually diminish over time.
Has Alaska had earthquakes this big before?
The largest recorded earthquake in Alaska was the M9.2 Great Alaska earthquake of March 27, 1964. Today's magnitude 4.5 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us6000u3tn). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2026, October 21, 2026). M4.5 Earthquake 158 km S of False Pass, Alaska — October 21, 2026. Retrieved October 21, 2026 from https://www.earthquaketracker.org/earthquakes/event/us6000u3tn/